A single facility can have hundreds, if not thousands, of valves to control everything from turbine operation to ventilation, to systems that ensure the safety of personnel and equipment. The valves used can range in size from less than an inch to several feet in diameter. While some of these valves are designed to be operated manually, many of them require some form of automatic or remote operation. Operators and technicians must understand the different types of actuators used to operate these valves, and how these actuators work.